I'm back into it as well. Let me give you what I've done and learned from this forum.
If you are airbrushing, Tamiya colors are the way to go, If brushing, Testors. Tamiya are almost the perfect consistency for AB and dry real fast. Testors take longer so are, to me, more appropriate for brushing. I'm not sure about using the spray cans. The only experience I've had with the cans is Tamiya's Metal Primer. And One More Time, IT'S BLEEDIN' CLEAR! (Sorry but clear primer still gets me, I think I got robbed).
Some people, me included, preshade. Spray a dark brown or black before your Dunkelgelb basecoat, Tamiya's flat black is great through an AB as a primer, no thinning at all.
Some people post shade. They spray a lighter coat on after to highlight. Either is fine.
There's also been much talk about using silly putty for masking camo patterns, try it.
A dullcoat can be applied to seal weathering and such on top of a variety of materials.
Good luck and welcome.
Hopefully someone will add and/or correct my info.